In previous research, we found that infants readily learned to move an overhead crib mobile by means of their own footkicks, and when presented with the non-moving mobile on subsequent days would exhibit high rates of footkicking indexing retention of the learned association. After periods of 2-4 weeks, when the association appeared forgotten during these "cued-recall" tests, presentation of a "reminder" from the original training context (i.e., the moving mobile) in a brief, non-contingent fashion alleviated the forgetting and restored conditioned responding to the high posttraining level during cued recall tests for periods up to 3+ days following the reminder or reactivation treatment. The present proposal seeks to extend the age range of infants to whom the previous procedures have been applied from 1-12 months with a conditioned sucking paradigm involving the same reinforcer (mobile movement), to explore the nature of the reactivation phenomenon more fully using the kick paradigm with 2-4 mo. olds, and to assess the effects of various training factors (distribution of training, interference, amount of training, distinctiveness of training context and role of session onset cues, etc.) on newly acquired and reactivated memories. These data will provide our only information about the relation of learning and memory in infants so young and our only information about the efficacy of reactivation in maintaining early memories. The learning and retention norms, and ontogenetic performance in reactivation tasks, may permit clinicians and caregivers to assess the effects of intervention procedures on subsequent performance and provide a means by which to screen exceptional infants and diagnose early learning, attentional, or memory deficits at very early ages, before the long-term effects of such deficits have had an impact which is difficult to overcome through intervention measures. In addition, these studies will contribute to our knowledge of memory and early development.